Six-Element Optical Lens Thermal Stability
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Solution Overview
Problem
Existing optical imaging lenses face challenges in maintaining good imaging quality and low back focal length variation across different ambient temperatures, while also matching the chief ray angle (CRA) with the corresponding image sensor, which is essential for various applications such as dashboard cameras and environmental surveillance.
Innovation Solution
The design of an optical imaging lens comprising a sequence of lens elements with specific refractive powers and surface shapes, including concave and convex portions, arranged to satisfy the condition (G12+G34+G45+G56)/G23≤1.500, ensuring a small CRA and low back focal length variation, thereby achieving thermal stability and improved imaging quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the optical imaging lens is miniaturized to reduce volume, then the volume is reduced, but the imaging quality deteriorates
Solution Approach 1:
The optical imaging lens is divided into six lens elements with different refractive powers and surface shapes. Each lens element is designed with specific concave or convex portions to correct aberrations and maintain imaging quality while reducing overall lens volume. The segmentation allows complex optical functions to be distributed across multiple simpler elements.
Solution Approach 2:
Different lens elements are designed with specific local surface features (concave or convex portions at object-side or image-side surfaces) to address specific optical aberrations. The third lens element has a concave object-side surface, the fifth lens element has a convex object-side surface, and the sixth lens element has a concave image-side surface, creating localized optical corrections throughout the compact lens structure.
2Length of moving object
If the back focal length is reduced to achieve compact design, then the volume is reduced, but the CRA matching with image sensor becomes difficult
Solution Approach 1:
The patent employs specific parameter relationships between lens elements to achieve both compact back focal length and proper CRA matching. The conditional expression (G12+G34+G45+G56)/G23≤1.500 defines a parameter relationship that controls the distribution of air gaps between lens elements, optimizing both back focal length and CRA characteristics simultaneously.
Solution Approach 2:
The lens design incorporates dynamic adjustment of light ray angles through the sequential arrangement of lens elements with varying refractive powers. The positive and negative refractive power elements work together to dynamically redirect chief rays to achieve the required CRA matching while maintaining a short back focal length.
3Device complexity
If the lens structure is simplified to reduce complexity, then the manufacturing is easier, but the thermal stability of back focal length deteriorates
Solution Approach 1:
The optical imaging lens uses a composite structure of six lens elements with alternating positive and negative refractive powers. This composite design creates thermal compensation effects where the different materials and structures respond differently to temperature changes, collectively maintaining stable back focal length despite individual element variations.
Solution Approach 2:
The positive and negative refractive power lens elements act as optical counterweights to each other. When temperature changes cause focal length variations in one element, the opposing refractive power elements compensate for these variations, maintaining overall back focal length stability without requiring complex active control mechanisms.
4Manufacturing precision
If multiple lens elements are added to improve imaging quality, then the imaging quality is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple optical functions into a compact six-element lens structure. Each lens element performs multiple functions: refraction, aberration correction, and chief ray angle control. The merging of these functions into a single integrated lens assembly achieves high imaging quality without the complexity of separate optical components.
Solution Approach 2:
Each lens element in the six-element assembly is designed with universal functionality to handle multiple optical tasks. The elements with positive and negative refractive powers serve both to focus light and correct various aberrations simultaneously, reducing the need for additional specialized components and simplifying the overall system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The lens elements with concave/convex shape designs provide a suitable CRA matching the image sensor and maintain low back focal length variation at different temperatures, resulting in enhanced imaging quality and thermal stability, effectively addressing the limitations of existing lenses.
Implementation Method 1
Each of the first to the sixth lens elements includes an object-side surface facing the object side and allowing imaging rays to pass through and an image-side surface facing the image side and allowing the imaging rays to pass through
Implementation Method 2
The third lens element has a negative refractive power. The fourth lens element has a positive refractive power
Data Source
AI summary
An imaging lens includes first, second, third, fourth, fifth and six lens elements arranged in order from an object side to an image side along an optical axis. Each lens element has an object-side surface and an image-side surface. The image-side surface of the second lens element has a concave portion in a vicinity of the optical axis. The third lens element has negative refractive power. The object-side surface of the third lens element has a concave portion in a vicinity of the optical axis. The object-side surface of the fifth lens element has a convex portion in a vicinity of a periphery. All lens elements of the imaging lens having the refractive power are only the first, second, third, fourth, fifth and six lens elements.